Location of indoor mini split unit - exterior or interior wall?

13 years ago

We are putting mini-splits in our house and have had 3 installers out to talk to us. Two said you have to put the indoor units on an exterior wall so the lines can run on the outside of the house. But one installer said he can run the lines through the basement (its unfinished) and up an interior wall so that we don't have the lines on the outside of the house. When I asked one of the other two installers about running the lines inside an interior wall, he said he NEVER does that because if they leak, they will leak in your wall, and servicing the lines means cutting a hole in your wall.

That does make sense to me, but the recommending the interior wall" option seemed much more knowledgeable in general about the systems, so now I don't know who is right. Does anyone have an opinion here?

Thx

Sort by:Oldest

Comments (5)

chrisny
13 years ago
Follow your instincts, the install who you felt was more knowledgeable IS. The other two are just lazy.

The correct location will be based on where you want the evaporator.

While MUCH easier to just poke your linesets out an exterior wall it is not true that putting it on an interior wall would require ripping up the wall to repair any leaks as all of the connections can be done externally of the wall in a cavity in the back of the evaporator.As long as the drain line is pitched correctly and the flares are nice and tight it is unlikely to leak anyway.

Also poking them through on an exterior wall will make the linesets visible going down the side of the house.
pkguy
13 years ago
I just had my replacement split unit installed today in the same place the original was.. on an interior wall overtop of the stairway leading up to the bedrooms.
My lines go down partially in the wall then into my basement furnaceroom then across the the rek room up above the ceiling tiles and to the unit outside at the back.. about a 40 ft trip in all.
I was never told any of that in fact one guy quoting pointed out that it might give better airflow if I had it moved to the opposite end of the room (an outside wall) but I like it where it is.. more out of sight.

I had 3 quotes and only one of them was any good and sort of knew what he was talking about and selling.. The other two, from local reputable companies, didn't seem to have much knowledge on them.. heck I knew more than they did and that's not much.
Related Discussions
Mini-splits throughout the house?
Q
Comments (12)
You say you will use these for cooling as you have the radiators, but I think you will find that you end up running your boiler only when it get really cold. Heating performance on these mshp's is outstanding. I heat and cool my home with Fujitsu's and Rinnai Energysavers. I pulled the entire central system, not because of poor equipment but because of very poor ductwork. I was the rep for Fujitsu for 12 yrs prior to selling my business and moving west. They make great equipment. It is difficult to advise without a floor plan, but as I see it, you have a few choices. You could go with a multi 2, 3, 4 or up to 8 evaporators on one outdoor condensing unit. Those tonnages can go 1.5, 2, 3, or 4 and the interior unit combinations and evaporator styles can mix and match. One thing I will say about the cassettes. Make sure you have service access. I concur with Ionize on the mini-ducted unit. they can work out very well in the transoms over closet doors and in attic areas. I hands down prefer the wall unit and find that they, just like everything else in the house blend in over time. The longer you live with them the better looking they become. You choice, but I think they are the best. I actually did a daily extensive, but informal, study on this. many times if I was involved at the beginning of the job and was told, "none of those ugly high wall units", when, for one rason or another they were installed I would go back after a while to see how they were. The comments were universally positive. Grudgingly so, at times, but people were happy with them. Mini splits are tremendous for dehumidification. I installed a dual system upstairs. I went with singles downstairs. These represent the ultimate in zone control, so we rarely run the upstairs units a lot. Downstairs I run a 25 seer 12RLS and I think it is a 21 seer 15RLS. That to me is the right combination. Very highest efficiency units in the primary living area and combis in the less used areas. Do not have a unit blowing right down on top of the bed. The cassettes can be 2, 3 or 4 way blows so that is adjustable. i'd suggest that you look at fujitsugeneral.com. Go to the Contractors tab and there you can download the entire catalog and they are very good about publishing specs. As to the hi-velocity units. They work. They are installation sensitive in the ducting and they are much less efficient. When the 13 seer mandate went into effect the hi-v folks used an exclusion (confined space) to not have to meet it. In my experience they cannot compare to mini-splits for either comfort or efficiency. As with so many things mechanical, hire the best guy you can find and pay him what he is asking. Having made a lot of site visits on problem installs I can tell you that there is no substitute for "do it right the first time" on these.
...See More
Mini Split overcools
Q
Comments (15)
I just purchased 2 split a/c systems as an upgrade from the units I currently have. It is now September 22, 2014 and I am unhappy with my 3 month old brand new units. I started with a Fujitsu 11000 btu in the master bedroom and a Mitsubishi 30000 btu in the living room. The Fujitsu was weak in cooling efficiency and even though I cared for it very well it required cleaning and servicing every 6 months. The living room was an older model - but if you set it at 71 degrees - we'd be freezing within the 1st hour. Both eventually had freon leaks. I replaced the bedroom with a 2014 Mitsubishi 15000 btu thinking I could run it on a low and quiet fan setting at night. The living room was changed to a 36 000 btu 2014 Mitsubishi which I was also hoping to run on a quieter setting. But - NO! We are running both of these units on MAX 59 degrees on a high fan to cool either room which takes a couple of hours. The air feels cold coming out of units - but not too far from the units. Recalled the installers and checked the freon, temps, and the workings of these. 2 month old units. "everything is Normal". Tech says that's how these new energy efficient units run. He says you gotta run them on max to start with or before the house heats up during the day or close the doors down the hallway to trap the cooler air in the living room. The bedroom is the same - we sleep at 9pm - so we run it at 7pm - on MAX!! It sucks - in Hawaii both units plus the install $6200. My electric bill is slightly higher because these energy efficient units run longer and on Max!!! So disappointing! I have tried different temp settings and combinations of fan power. Some have suggested that in Max mode- it is bouncing the cold air off the opposite wall back to the unit causing the thermostat to raise the temp. I am baffled - so junk !!!
...See More
Mini Split Heat Pump / How Many Units
Q
Comments (14)
Thanks for the location. Certainly some variation in local climate it seems. What elevation are you at? All things are relative and "cold, mountainous" would be 2 of those terms. Looks like average winter low is about 15 degrees. "Pretty good insulation" would also be relative. How old is the house gives some estimate. Having electric baseboard that far North would probably mean at least 50 years old. I mean I have lived in some very old houses (that would be 100 years old now) in Buffalo and Ithaca and had electric baseboard one time. Sizing is determined by both cooling and heating. Generally - a northern area where heating dominates, the sizing is by heating. Where I live, it is still usually heating despite what people think. But large western windows can change that. Bias alert. I think HVAC folks are going to encourage multiple units and I doubt you "need" them. You could spend $4000 on a single unit and get payback in 2 years. Your could spend $8000 on 2 units and get payback on the second unit - never. But the HVAC guy gets payback right away. Are you living there year round? And, adding to what Charles said - are you open to adding ductwork or not? Are you open to other fuels? I think a minisplit will probably be the best but there are other choices. Probably more like $20k rather than $4k.
...See More
Ductless mini-split for high-rise condo
Q
Comments (9)
You might be able to put the compressor unit on the balcony, and then feed refrigerant to a unit on the inside wall abutting the balcony. Let it cool everything, or else you have to pay for more expander heads and the plumbing. Also the heads have to drain, and I will be happy to regale you with possible issues associated with doing so. A few years ago (in NH) I had installed two Mitsubishi systems, one 4-head and one 2-head. Four of these heads are on interior walls. I think the price was near $20k to cool 2600 sq. ft. If you are only supplementing the building AC in the summer, and doing moderate cooling in the fall, you may not need a very powerful unit. I can say that the compressors and the heads are very quiet. You can hear the fan at the outdoor compressor. It is about as loud as a window fan on low. At one point one compressor developed an intermittent racket, fixed by some adjustment, when the compressor iced up trying to pull heat from near freezing humid air. They are designed to de-ice, but I think between fan alignment and ice build-up there was a bit of overlap that needed to be adjusted. You will need a hole in the wall to contain two refrigerant lines and a control power line. The lines to the compressor unit will be covered by a plastic cover. You will need an outdoor disconnect switch and power feed of 20 to 40 amperes at 240 Vac. Your balcony may be subject to a warm air breeze from the compressor unit, depending how it is placed.
...See More
hrhkee_msn_com
12 years ago
I need to put a dual head unit in my basement in two interior rooms. Mitsubishi advertises that I can run the drainage UP to the plenum space and angle it two rooms away to the ouside wall. The manuals for their minisplit, ymg sanyo and klimaire says not to do it. How may I use a pump to accomplish this. The floor is concrete. Also closest drainage is a bathroom. Can I drain them there?
brickeyee
12 years ago
"I need to put a dual head unit in my basement in two interior rooms. Mitsubishi advertises that I can run the drainage UP to the plenum space and angle it two rooms away to the ouside wall. The manuals for their minisplit, ymg sanyo and klimaire says not to do it. How may I use a pump to accomplish this. The floor is concrete. Also closest drainage is a bathroom. Can I drain them there?"

All you need is a small condensate pump and you can run the lines nearly anywhere.

The small pumps have a tank to collect the condensate, a level switch to determine when to turn on the pump, and a pump.

The line can often be as small as 1/2 inch flexible plastic tubing.
It can run into just about any drain, but it requires an 'indirect waste.'

That means the tube ends above the flood level of the drain or sink.

A nearby laundry sink is a good option.
airstarsolutions
12 years ago
There is some truth to both interior and exterior installations. Exterior, clearly easier and they were correct to tell you that there is a potential to leak and damage your walls / floors / etc. A lazy technician may not pay attention to detail taping up the seams of the insulation they are using on the copper. We switched and only used a seamless pre-insulated copper...works great.

As for the pump / drain issues - look up 'Aspen Pumps' they have the right pump for any mini-split installation.

Location of indoor mini split unit - exterior or interior wall?

Comments (5)

chrisny

pkguy

Related Discussions

hrhkee_msn_com

brickeyee

airstarsolutions

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US